Heroku build fails on uglifier

Question

My minimal app runs locally and I have no bundle errors. When I push to heroku, however, the build fails during assets:precompile step:

...
Bundle completed (3.24s)
Cleaning up the bundler cache.
-----> Preparing app for Rails asset pipeline
Running: rake assets:precompole
rake aborted!
LoadError: cannot load such file -- uglifier
(in /tmp/build_.../app/assets/javascripts/application.js)

Notes:
1. I am not using the uglifier gem locally
2. I do not have a file app/assets/javascripts/application.js

I have tried these Gemfile solutions:
A) adding the uglifier gem
B) adding uglifier to the assets group
C) removing uglifier completely from Gemfile and rake uninstall all versions

What's next?

check if you have javascript error on the browser console. Try precompile on local machine. — pkrawat1, Dec 26 '14 at 17:13
The precompile locally works except for pg_ext, which seems to be a different issue than uglifier. What I don't understand is why uglifier is being referenced at all since I removed it from the Gemfile and uninstalled all versions?? — vbsql7, Dec 26 '14 at 17:47

score 19 · Answer 1 · answered Feb 08 '16 at 16:28

19

A better solution, if you want to compress your assets, is to add uglifier to your GEMFILE:

gem 'uglifier'

answered Feb 08 '16 at 16:28

mindtonic

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score 14 · Accepted Answer · answered Dec 26 '14 at 19:38

14

Comment this line in config/environments/production.rb

config.assets.js_compressor = :uglifier

answered Dec 26 '14 at 19:38

pkrawat1

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Do not forget to commit before the next push! :-) – Lucio Jan 07 '15 at 18:59

score 6 · Answer 3 · answered Nov 28 '18 at 11:31

If you're interested in continuing to use uglifier, you can add it to your Gemfile (and install with Bundler) -- as explained by @mindtonic.

Also, if you're using ES6, you'll need to switch:

config.assets.js_compressor = :uglifier

to:

config.assets.js_compressor = Uglifier.new(harmony: true)

As explained in https://github.com/lautis/uglifier/issues/127

score 1 · Answer 4 · edited Feb 11 '21 at 18:49

1

You have to focus on two points:

Point 1. Version of the Gem: This should be 4.2

gem 'uglifier', '~> 4.2'

Point 2. Use js compressor now

config.assets.js_compressor = Uglifier.new(harmony: true)

edited Feb 11 '21 at 18:49

Dharman

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answered Feb 11 '21 at 18:43

Jai Chauhan

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The version bump was the important part for me. Thanks – dave paola Sep 19 '22 at 19:31

Heroku build fails on uglifier

4 Answers4